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Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
21.02.2025/Kiel/Mindelo. Last weekend, the expedition M208 led by the GEOMAR Helmholtz Centre for Ocean Research Kiel started. The expedition with the research vessel METEOR is investigating the physical, chemical and biological processes in the coastal upwelling region off Northwest Africa. The aim is to gain a better understanding of the interactions between the ocean, atmosphere and marine ecosystems. The expedition also serves as preparation for the large-scale FUTURO project, which will focus on the further development of the ecosystem off Northwest Africa from 2027.
Coastal upwelling areas on the eastern margins of the Atlantic and Pacific are among the most biologically productive regions of the ocean and are of great ecological and socio-economic importance. They have a significant influence on the global climate, but are sensitive to human influences such as ocean warming, ocean acidification and oxygen deprivation.
In order to better understand these complex processes, an in-depth scientific description of coastal upwelling systems is needed. The METEOR expedition M208 “NowUP”, which has now been launched under the leadership of the GEOMAR Helmholtz Centre for Ocean Research Kiel, will make an important contribution to this. The name of the expedition stands for Northwest African Upwelling and Productivity. It is making initial preparations for the international observation campaign FUTURO (The Future of Tropical Upwelling Region in the Atlantic Ocean), which is to be carried out off Northwest Africa from 2027 to 2029.
Physical drivers of biological productivity
The high productivity in the upwelling area off Northwest Africa is driven by the southerly wind along the coast. This wind causes an offshore transport of near-surface water, which is replaced by deeper, nutrient-rich water. Other physical processes can also play an equally important role. These include, for example, boundary waves generated at the equator or along the coasts of the Gulf of Guinea, which may lead to upwelling of nutrient-rich water off Northwest Africa, or mixing on the shelf caused locally by internal tides. With a combination of different measurement systems, which are used continuously during the cruise or at stations, as well as through the deployment of autonomous gliders and moorings, the complex dynamics in the upwelling area will be studied during "NowUP" in order to draw conclusions about possible future changes.
Interaction between ocean and atmosphere
The atmosphere influences the biological productivity of the sea through the input of huge quantities of Saharan dust, which supplies essential nutrients such as phosphate and iron. These promote the growth of phytoplankton, which serves as the basis of the marine food web and plays an important role as an oxygen producer and CO₂ sink. How exactly the tiny dust particles influence the biological and chemical processes in the water is one of the central questions of the METEOR expedition M208. The meteorological conditions under which dust outbreaks occur are also being investigated. “February and March are a favourable time for our expedition,” says expedition leader Dr Peter Brandt, Professor of Physical Oceanography at GEOMAR. “During this time, biological productivity is maximised by stronger winds and at the same time Saharan dust storms occur.”
Nutrients from desert dust drive the “biological pump”
The “biological pump” is crucial for the global carbon cycle. The term “biological pump” describes the absorption of CO₂ from the atmosphere by microscopic algae (phytoplankton) to build up their biomass and the subsequent export of the bound carbon to greater water depths. Here, this carbon is then stored for hundreds of years and removed from the climate system. The build-up of phytoplankton biomass is supported by nutrients such as nitrogen and phosphorus, which are brought to the surface by upwelling off Northwest Africa, as well as trace elements from Saharan dust. This biomass is exported in various ways. For example, small animals drifting in the sea (zooplankton) eat the phytoplankton and excrete faecal pellets that sink into the ocean. Dying phytoplankton can also form aggregates and sink as marine snow. In addition, daily vertical migrations of zooplankton from the surface to depths of around 200 to 600 metres contribute to additional carbon displacement.
Various measurements planned
The scientists will use various instruments for their investigations, including to measure the salt and oxygen concentration, temperature, nutrient-, iron-, phyto-, zooplankton- and particle distribution.
- Anchored instruments to determine currents, internal waves and carbon flux
- Gliders measure autonomously during the ship's campaign and can record hydrography, particles and zooplankton of marine areas
- Real-time satellites help to identify dynamic structures and better plan ship measurements
- ADCP (Acoustic Doppler Current Profiler) to acoustically measure the speed of ocean currents at different water depths
- Microstructure probes measure mixing in the ocean
- Moving Vessel Profiler (MVP) measures water properties (e.g. temperature, salinity and chlorophyll) from a moving research vessel
- Radiosondes ascend into the atmosphere with balloons to measure temperature, humidity, pressure and wind at different altitudes
- Sensors from the Portable Meteorological Observatory (PortMeteO) record weather conditions and dust transport
Expedition M208 aims to better understand the interactions between upwelling, dust input, phytoplankton growth and carbon export and thus enable more precise predictions about the effects of climate change on coastal upwelling systems.
http://www.geomar.de/n9774 Images available for download
https://www.geomar.de/forschen/expeditionen/detailansicht/exp/376722?cHash=2cc9f... METEOR M208
https://www.geomar.de/en/centre/research-in-cape-verde Research on Cabo Verde
https://futuro-campaign.org/ FUTURO campaign
Merkmale dieser Pressemitteilung:
Journalisten
Biologie, Chemie, Meer / Klima, Umwelt / Ökologie
überregional
Buntes aus der Wissenschaft, Forschungsprojekte
Englisch
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